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//#define QIMAGEREADER_DEBUG

/*!

    \class QImageReader

    \brief The QImageReader class provides a format independent interface

    for reading images from files or other devices.

    \reentrant

    \ingroup painting

    \ingroup io

    The most common way to read images is through QImage and QPixmap's

    constructors, or by calling QImage::load() and

    QPixmap::load(). QImageReader is a specialized class which gives

    you more control when reading images. For example, you can read an

    image into a specific size by calling setScaledSize(), and you can

    select a clip rect, effectively loading only parts of an image, by

    calling setClipRect(). Depending on the underlying support in the

    image format, this can save memory and speed up loading of images.

    To read an image, you start by constructing a QImageReader object.

    Pass either a file name or a device pointer, and the image format

    to QImageReader's constructor. You can then set several options,

    such as the clip rect (by calling setClipRect()) and scaled size

    (by calling setScaledSize()). canRead() returns the image if the

    QImageReader can read the image (i.e., the image format is

    supported and the device is open for reading). Call read() to read

    the image.

    If any error occurs when reading the image, read() will return a

    null QImage. You can then call error() to find the type of error

    that occurred, or errorString() to get a human readable

    description of what went wrong.

    Call supportedImageFormats() for a list of formats that

    QImageReader can read. QImageReader supports all built-in image

    formats, in addition to any image format plugins that support

    reading.

    QImageReader autodetects the image format by default, by looking at the

    provided (optional) format string, the file name suffix, and the data

    stream contents. You can enable or disable this feature, by calling

    setAutoDetectImageFormat().

    \sa QImageWriter, QImageIOHandler, QImageIOPlugin

*/

/*!

    \enum QImageReader::ImageReaderError

    This enum describes the different types of errors that can occur

    when reading images with QImageReader.

    \value FileNotFoundError QImageReader was used with a file name,

    but not file was found with that name. This can also happen if the

    file name contained no extension, and the file with the correct

    extension is not supported by Qt.

    \value DeviceError QImageReader encountered a device error when

    reading the image. You can consult your particular device for more

    details on what went wrong.

    \value UnsupportedFormatError Qt does not support the requested

    image format.

    \value InvalidDataError The image data was invalid, and

    QImageReader was unable to read an image from it. The can happen

    if the image file is damaged.

    \value UnknownError An unknown error occurred. If you get this

    value after calling read(), it is most likely caused by a bug in

    QImageReader.

*/

#include "qimagereader.h"

#include <qbytearray.h>

#ifdef QIMAGEREADER_DEBUG

#include <qdebug.h>

#endif

#include <qfile.h>

#include <qfileinfo.h>

#include <qimage.h>

#include <qimageiohandler.h>

#include <qlist.h>

#include <qrect.h>

#include <qset.h>

#include <qsize.h>

#include <qcolor.h>

#include <qvariant.h>

// factory loader

#include <qcoreapplication.h>

#include <private/qfactoryloader_p.h>

// image handlers

#include <private/qbmphandler_p.h>

#include <private/qppmhandler_p.h>

#include <private/qxbmhandler_p.h>

#include <private/qxpmhandler_p.h>

#ifndef QT_NO_IMAGEFORMAT_PNG

#include <private/qpnghandler_p.h>

#endif

QT_BEGIN_NAMESPACE

#ifndef QT_NO_LIBRARY

Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, loader,

                          (QImageIOHandlerFactoryInterface_iid, QLatin1String("/imageformats")))

#endif

enum _qt_BuiltInFormatType {

#ifndef QT_NO_IMAGEFORMAT_PNG

    _qt_PngFormat,

#endif

    _qt_BmpFormat,

#ifndef QT_NO_IMAGEFORMAT_PPM

    _qt_PpmFormat,

    _qt_PgmFormat,

    _qt_PbmFormat,

#endif

#ifndef QT_NO_IMAGEFORMAT_XBM

    _qt_XbmFormat,

#endif

#ifndef QT_NO_IMAGEFORMAT_XPM

    _qt_XpmFormat,

#endif

    _qt_NumFormats,

    _qt_NoFormat = -1

};

struct _qt_BuiltInFormatStruct

{

    _qt_BuiltInFormatType type;

    const char *extension;

};

static const _qt_BuiltInFormatStruct _qt_BuiltInFormats[] = {

#ifndef QT_NO_IMAGEFORMAT_PNG

    {_qt_PngFormat, "png"},

#endif

    {_qt_BmpFormat, "bmp"},

#ifndef QT_NO_IMAGEFORMAT_PPM

    {_qt_PpmFormat, "ppm"},

    {_qt_PgmFormat, "pgm"},

    {_qt_PbmFormat, "pbm"},

#endif

#ifndef QT_NO_IMAGEFORMAT_XBM

    {_qt_XbmFormat, "xbm"},

#endif

#ifndef QT_NO_IMAGEFORMAT_XPM

    {_qt_XpmFormat, "xpm"},

#endif

    {_qt_NoFormat, ""}

};

static QImageIOHandler *createReadHandlerHelper(QIODevice *device,

                                                const QByteArray &format,

                                                bool autoDetectImageFormat,

                                                bool ignoresFormatAndExtension)

{

    if (!autoDetectImageFormat && format.isEmpty())

        return 0;

    QByteArray form = format.toLower();

    QImageIOHandler *handler = 0;

#ifndef QT_NO_LIBRARY

    // check if we have plugins that support the image format

    QFactoryLoader *l = loader();

    QStringList keys = l->keys();

#endif

    QByteArray suffix;

#ifdef QIMAGEREADER_DEBUG

    qDebug() << "QImageReader::createReadHandler( device =" << (void *)device << ", format =" << format << "),"

             << keys.size() << "plugins available: " << keys;

#endif

#ifndef QT_NO_LIBRARY

    int suffixPluginIndex = -1;

    if (device && format.isEmpty() && autoDetectImageFormat && !ignoresFormatAndExtension) {

        // if there's no format, see if \a device is a file, and if so, find

        // the file suffix and find support for that format among our plugins.

        // this allows plugins to override our built-in handlers.

        if (QFile *file = qobject_cast<QFile *>(device)) {

#ifdef QIMAGEREADER_DEBUG

            qDebug() << "QImageReader::createReadHandler: device is a file:" << file->fileName();

#endif

            if (!(suffix = QFileInfo(file->fileName()).suffix().toLower().toLatin1()).isEmpty()) {

                int index = keys.indexOf(QString::fromLatin1(suffix));

                if (index != -1) {

#ifdef QIMAGEREADER_DEBUG

                    qDebug() << "QImageReader::createReadHandler: suffix recognized; the"

                             << suffix << "plugin might be able to read this";

#endif

                    suffixPluginIndex = index;

                }

            }

        }

    }

#endif // QT_NO_LIBRARY

    QByteArray testFormat = !form.isEmpty() ? form : suffix;

    if (ignoresFormatAndExtension)

        testFormat = QByteArray();

#ifndef QT_NO_LIBRARY

    if (suffixPluginIndex != -1) {

        // check if the plugin that claims support for this format can load

        // from this device with this format.

        const qint64 pos = device ? device->pos() : 0;

        QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(QString::fromLatin1(suffix)));

        if (plugin && plugin->capabilities(device, testFormat) & QImageIOPlugin::CanRead) {

            handler = plugin->create(device, testFormat);

#ifdef QIMAGEREADER_DEBUG

            qDebug() << "QImageReader::createReadHandler: using the" << suffix

                     << "plugin";

#endif

        }

        if (device && !device->isSequential())

            device->seek(pos);

    }

    if (!handler && !testFormat.isEmpty() && !ignoresFormatAndExtension) {

        // check if any plugin supports the format (they are not allowed to

        // read from the device yet).

        const qint64 pos = device ? device->pos() : 0;

        if (autoDetectImageFormat) {

            for (int i = 0; i < keys.size(); ++i) {

                if (i != suffixPluginIndex) {

                    QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(keys.at(i)));

                    if (plugin && plugin->capabilities(device, testFormat) & QImageIOPlugin::CanRead) {

#ifdef QIMAGEREADER_DEBUG

                        qDebug() << "QImageReader::createReadHandler: the" << keys.at(i) << "plugin can read this format";

#endif

                        handler = plugin->create(device, testFormat);

                        break;

                    }

                }

            }

        } else {

            QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(QLatin1String(testFormat)));

            if (plugin && plugin->capabilities(device, testFormat) & QImageIOPlugin::CanRead) {

#ifdef QIMAGEREADER_DEBUG

                qDebug() << "QImageReader::createReadHandler: the" << testFormat << "plugin can read this format";

#endif

                handler = plugin->create(device, testFormat);

            }

        }

        if (device && !device->isSequential())

            device->seek(pos);

    }

#endif // QT_NO_LIBRARY

    // if we don't have a handler yet, check if we have built-in support for

    // the format

    if (!handler && !testFormat.isEmpty()) {

        if (false) {

#ifndef QT_NO_IMAGEFORMAT_PNG

            handler = new QPngHandler;

#endif

#ifndef QT_NO_IMAGEFORMAT_BMP

        } else if (testFormat == "bmp") {

            handler = new QBmpHandler;

#endif

#ifndef QT_NO_IMAGEFORMAT_XPM

        } else if (testFormat == "xpm") {

            handler = new QXpmHandler;

#endif

#ifndef QT_NO_IMAGEFORMAT_XBM

        } else if (testFormat == "xbm") {

            handler = new QXbmHandler;

            handler->setOption(QImageIOHandler::SubType, testFormat);

#endif

#ifndef QT_NO_IMAGEFORMAT_PPM

        } else if (testFormat == "pbm" || testFormat == "pbmraw" || testFormat == "pgm"

                   || testFormat == "pgmraw" || testFormat == "ppm" || testFormat == "ppmraw") {

            handler = new QPpmHandler;

            handler->setOption(QImageIOHandler::SubType, testFormat);

#endif

        }

#ifdef QIMAGEREADER_DEBUG

        if (handler)

            qDebug() << "QImageReader::createReadHandler: using the built-in handler for" << testFormat;

#endif

    }

#ifndef QT_NO_LIBRARY

    if (!handler && (autoDetectImageFormat || ignoresFormatAndExtension)) {

        // check if any of our plugins recognize the file from its contents.

        const qint64 pos = device ? device->pos() : 0;

        for (int i = 0; i < keys.size(); ++i) {

            if (i != suffixPluginIndex) {

                QImageIOPlugin *plugin = qobject_cast<QImageIOPlugin *>(l->instance(keys.at(i)));

                if (plugin && plugin->capabilities(device, QByteArray()) & QImageIOPlugin::CanRead) {

                    handler = plugin->create(device, testFormat);

#ifdef QIMAGEREADER_DEBUG

                    qDebug() << "QImageReader::createReadHandler: the" << keys.at(i) << "plugin can read this data";

#endif

                    break;

                }

            }

        }

        if (device && !device->isSequential())

            device->seek(pos);

    }

#endif // QT_NO_LIBRARY

    if (!handler && (autoDetectImageFormat || ignoresFormatAndExtension)) {

        // check if any of our built-in handlers recognize the file from its

        // contents.

        int currentFormat = 0;

        if (!suffix.isEmpty()) {

            // If reading from a file with a suffix, start testing our

            // built-in handler for that suffix first.

            for (int i = 0; i < _qt_NumFormats; ++i) {

                if (_qt_BuiltInFormats[i].extension == suffix) {

                    currentFormat = i;

                    break;

                }

            }

        }

        QByteArray subType;

        int numFormats = _qt_NumFormats;

        while (device && numFormats >= 0) {

            const _qt_BuiltInFormatStruct *formatStruct = &_qt_BuiltInFormats[currentFormat];

            const qint64 pos = device->pos();

            switch (formatStruct->type) {

#ifndef QT_NO_IMAGEFORMAT_PNG

            case _qt_PngFormat:

                if (QPngHandler::canRead(device))

                    handler = new QPngHandler;

                break;

#endif

#ifndef QT_NO_IMAGEFORMAT_BMP

            case _qt_BmpFormat:

                if (QBmpHandler::canRead(device))

                    handler = new QBmpHandler;

                break;

#endif

#ifndef QT_NO_IMAGEFORMAT_XPM

            case _qt_XpmFormat:

                if (QXpmHandler::canRead(device))

                    handler = new QXpmHandler;

                break;

#endif

#ifndef QT_NO_IMAGEFORMAT_PPM

            case _qt_PbmFormat:

            case _qt_PgmFormat:

            case _qt_PpmFormat:

                if (QPpmHandler::canRead(device, &subType)) {

                    handler = new QPpmHandler;

                    handler->setOption(QImageIOHandler::SubType, subType);

                }

                break;

#endif

#ifndef QT_NO_IMAGEFORMAT_XBM

            case _qt_XbmFormat:

                if (QXbmHandler::canRead(device))

                    handler = new QXbmHandler;

                break;

#endif

            default:

                break;

            }

            if (!device->isSequential())

                device->seek(pos);

            if (handler) {

#ifdef QIMAGEREADER_DEBUG

                qDebug() << "QImageReader::createReadHandler: the" << formatStruct->extension

                         << "built-in handler can read this data";

#endif

                break;

            }

            --numFormats;

            ++currentFormat;

            currentFormat %= _qt_NumFormats;

        }

    }

    if (!handler) {

#ifdef QIMAGEREADER_DEBUG

        qDebug() << "QImageReader::createReadHandler: no handlers found. giving up.";

#endif

        // no handler: give up.

        return 0;

    }

    handler->setDevice(device);

    if (!form.isEmpty())

        handler->setFormat(form);

    return handler;

}